A movable flap with a symmetric NACA foil serves as a common control surface for underwater marine vehicles. To augment the functionality of the control surface, a Tab-Assisted Control (TAC) surface was experimentally tested to address its benefits to various different requirements of the control surface. The advantage of the TAC surface could be further enhanced with Shape Memory Alloy (SMA) actuators to control the rear portion of the control surface to form a flexible tab (or FlexTAC) surface. Although the measured FlexTAC data demonstrated similar augmentation in enhancing an airfoil's functionality, they also show subtle differences in data obtained from the TAC and FlexTAC measurements. High fidelity hybrid unstructured Reynolds Averaged Navier Stokes (RANS) calculation results are used to define the flow fields associated with the multi-element FlexTAC foil with a stabilizer, a flap and a flexible tab. The prediction results are compared with the measured data obtained from both the TAC and the FlexTAC experiments. The comparison also leads to the resolution of the differences that existed between the two data sets. In addition the RANS solutions are validated for predicting the forces and moments acting on the hydrofoil with adequate accuracy for use with an optimization scheme. For a horizontal control surface to effectively provide upward and downward motions, it is necessary to maintain a symmetric foil shape. In order to achieve maximum benefit out of a horizontal TAC/FlexTAC surface, a shape modification of the stabilizer (fixed portion of the hydrofoil) and the flap is desirable to account for the requirements at the most severe scenario. This paper focuses on the conditions when the movable flap surface becomes jammed. Since the present investigation deals with a FlexTAC configuration with a flexible tab, the shape modification focuses only on the stabilizer and the non-flexible portions of the flap.